Re: [ccp4bb] RES: [ccp4bb] About model building

2023-11-06 Thread Sam Tang
I3 and > collect data at Cu wavelength for SAD phasing, which could help you to > resolve the missing piece. Maybe. > Cheers, > Boaz > > Boaz Shaanan, Ph.D. > Dept. of Life Sciences > Ben Gurion University > Beer Sheva, Israel > > On Nov 4, 2023 10:04, Sam Tang w

Re: [ccp4bb] About model building

2023-11-05 Thread Sam Tang
s spec of your crystal to identify the other protein. Once done > solve your structure and build the complete model. This should be straight > forward and quick. > > Best Wishes > > On Sat, 4 Nov 2023, 09:05 Sam Tang, wrote: > >> Dear community, >> >> I am solvin

[ccp4bb] About model building

2023-11-04 Thread Sam Tang
Dear community, I am solving the structure of a complex between proteins A and B, where A is a protein with known homologs and B is a novel protein isolated from plant. The diffraction data was at 1.9 Ang collected in-house, indexed to P321. Using A as the search model, we have got a reasonable

Re: [ccp4bb] Add hydrogens

2021-09-29 Thread Sam Tang
Have just tried out some of the options -- done within minutes! Many thanks for the numerous input! All the best Sam On Wed, 29 Sept 2021 at 19:03, Sam Tang wrote: > Dear community > > This may appear to be a silly question -- I am trying to add hydrogens to > the structure in

[ccp4bb] Add hydrogens

2021-09-29 Thread Sam Tang
Dear community This may appear to be a silly question -- I am trying to add hydrogens to the structure in PDB 1CDW. My initial thought is to run a single run of refinement with a refinement program. It happens that I cannot locate the map coefficients under the entry (am I missing something?)

[ccp4bb] off-topic: structural motif / domain comparison

2021-08-06 Thread Sam Tang
Dear all Sorry for an off-topic question here. I wonder if anyone may be aware of any search program which allows one to 'blast' a protein domain just like we 'blast' a protein sequence? For example I have an epitope in hand and would like to find out whether this also exists in other proteins.

Re: [ccp4bb] off-topic: glycans

2021-06-29 Thread Sam Tang
s* > > Senior Laboratory Research Scientist > > Signalling and Structural Biology Lab > > The Francis Crick Institute > > London, UK > > == > > Diamond User Committee (MX) > > CCP4 WG2 > > == > > about.me/david_briggs > --

[ccp4bb] off-topic: glycans

2021-06-28 Thread Sam Tang
Dear community Sorry for an off-topic question here. I wonder if anyone may be aware of any glycan modification database where we can predict what is what. For example, if I got a mass difference of m/z X on LC-MS, and I would like to have a rough idea what it might be, where should I go for?

Re: [ccp4bb] High Rs

2021-04-02 Thread Sam Tang
Dear all Thanks a lot for the numerous input. Will try the different strategies and get back again soon. BRs Sam On Thu, 1 Apr 2021 at 20:28, Sam Tang wrote: > Dear all > > I have a dataset processed to 2.2 A, P212121, with no major issues > identified by Xtriage (no tNCS,

[ccp4bb] High Rs

2021-04-01 Thread Sam Tang
Dear all I have a dataset processed to 2.2 A, P212121, with no major issues identified by Xtriage (no tNCS, no twinning, no ice ring, good completeness). Phaser-MR gave a good solution except some loop regions are shifted. There is only 1 molecule in the ASU (and seemingly no more molecule can be

[ccp4bb] unknown density

2021-03-22 Thread Sam Tang
Hello fellow colleagues Hope you are all well while the pandemics persists. I just wonder if anyone may have an idea what this density (looking like a pentagon) might be. The data was collected to 1.8 A and crystal was grown in Bis-tris + PEG3350. Imidazole residual? Nucleotide (the protein

[ccp4bb] Saving multi-state obj in Pymol

2021-01-30 Thread Sam Tang
Hi Not sure if it is the right place to go but I'm sure I can get some help here. I am trying to combine two multi-state objects and save it to a new object. It happens that the molecule is not correctly displayed after Save. Would anyone have an idea what may have gone wrong?

Re: [ccp4bb] PISA

2021-01-21 Thread Sam Tang
ing > all the DNA bases the same residue number. As you are using the old gui you > might be able to do the same with pdbset or pdbcur, or maybe a graphics > program. > > Cheers, Jon Cooper > > > Sent from ProtonMail mobile > > > > Original Messa

[ccp4bb] PISA

2021-01-20 Thread Sam Tang
Dear community I ran PISA from CCP4i to analyze a protein-ssDNA complex with non-standard modified nucleotides. It turns out that PISA identifies each nucleotide in the DNA chain as a ligand (i.e. I have 7 DNA bases and PISA calls out 7 ligands). May I solicit your experience if there is a way to

[ccp4bb] over-fitting? over-refinement?

2020-10-19 Thread Sam Tang
Hi, the question may be a bit weird, but how do you define 'over-fitting' in the context of structure refinement? From users' perspective the practical aspect is to 'fit' the model into the density. So there comes this question from our juniors: fit is fit, how is a model over-fit? BRS Sam

Re: [ccp4bb] Element type N+1

2020-10-16 Thread Sam Tang
.b.coo...@protonmail.com > > > > > > Original Message > On 16 Oct 2020, 06:57, Sam Tang < samtys0...@gmail.com> wrote: > > > Dear all > > I attach herewith the Arg concerned. I actually saw no issue in Coot when > I checked residue

Re: [ccp4bb] Element type N+1

2020-10-16 Thread Sam Tang
ed side chain and a normal one? > > Best wishes, Jon Cooper. jon.b.coo...@protonmail.com > > > > > > Original Message > On 15 Oct 2020, 15:07, Sam Tang < samtys0...@gmail.com> wrote: > > > Dear colleagues > > I am trying to refine a s

[ccp4bb] Element type N+1

2020-10-15 Thread Sam Tang
Dear colleagues I am trying to refine a structure with Refmac and the work completes without any warning. However I am a bit puzzled for one single N atom on an Arg residue the element type becomes N+1. This doesn't happen on my another NCS chain and the input PDB seems fine. Could anyone kindly

[ccp4bb] ccp4 and ccpEM on same workstation?

2020-04-30 Thread Sam Tang
Hi, I'm going to install ccpEM on a same fedora 30 workstation that already has ccp4 will they touch on my pre-existing Coot and Refmac setup? Maybe I'm just worrying too much..? Cheers Sam To unsubscribe from

[ccp4bb] disulfides in coot

2020-02-18 Thread Sam Tang
Dear all A very technical question which I believe a few simple mouse clicks would solve. Is there a way I can ask Coot not to build the disulfide linkage automatically (which lies within a strong red density)? My WinCoot is version 0.8.9.2 Many thanks! Regards Sam

Re: [ccp4bb] resolution

2019-07-05 Thread Sam Tang
? In this case do you think refining at a (much) lower resolution is acceptable? Best regards Sam On Fri, 5 Jul 2019 at 13:43, Sam Tang wrote: > Hello everyone > > Sorry for a naive question. Is there any circumstances where one may wish > to refine to a lower resolution? For example if one h

[ccp4bb] resolution

2019-07-04 Thread Sam Tang
Hello everyone Sorry for a naive question. Is there any circumstances where one may wish to refine to a lower resolution? For example if one has a dataset processed to 2 A, is there any good reasons for he/she to refine to only, say 2.5 A? Thanks! Sam Tang

Re: [ccp4bb] [EXTERNAL] Re: [ccp4bb] High Rfree - ice ring

2019-04-09 Thread Sam Tang
once for the low resolution data >> and once for the high. >> >> Harry >> -- >> Dr Harry Powell >> >> >> -- >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CC

Re: [ccp4bb] [EXTERNAL] Re: [ccp4bb] High Rfree - ice ring

2019-04-08 Thread Sam Tang
TERNAL] Re: [ccp4bb] High Rfree - ice ring > > > > > > Dear Sam, > > > > > > > > I would remove the ice ring and reprocess the data. Ice rings may wreak > havoc with scaling so at minimum you have to redo the scaling. > > > > > >

Re: [ccp4bb] High Rfree - ice ring

2019-04-04 Thread Sam Tang
than one copy per asymmetric unit, are you imposing NCS > restraints during refinement? > > -Eric > > > > On Wed, Apr 3, 2019 at 1:41 PM Sam Tang wrote: > >> Hi everyone again >> >> Hmmm I think we have solved a structure in P1 space, to 2.5 A. However >> af

[ccp4bb] High Rfree - ice ring

2019-04-03 Thread Sam Tang
Hi everyone again Hmmm I think we have solved a structure in P1 space, to 2.5 A. However after refinement the Rfree stuck at 33%-35% with Rwork around 26%. The structure was solved by MR and current model seems to fit density well. In Refmac log I found that at the resolution corresponding to

Re: [ccp4bb] Refmac dictionary

2019-04-02 Thread Sam Tang
Hi My apologies. This is indeed a silly question. It appears I forgot to remove the extra O when linking them together! Sam On Wed, 3 Apr 2019 at 07:21, Sam Tang wrote: > Dear all > > Hello again. > > We have another protein-RNA dataset which we are trying to refine. For &g

[ccp4bb] Refmac dictionary

2019-04-02 Thread Sam Tang
Dear all Hello again. We have another protein-RNA dataset which we are trying to refine. For this dataset we have three OMU nucleotides modelled. We got the monomer from Coot 'Get Monomer'. Refmac returned the following error: ERROR : atom :OP3 OMU 2 CCC is absent in the

[ccp4bb] modelling of modified RNA

2019-04-02 Thread Sam Tang
Hello I have been refining a protein-RNA complex with Refmac. The RNA we used was tagged with a Cy label. I modelled the RNA in Coot using the RCrane add-on and manually built the Cy tag. However after Refmac (also via Coot) the linkage between Cy and the RNA was always broken. I guess I must

Re: [ccp4bb] Weird diffraction pattern

2018-10-11 Thread Sam Tang
Dear all Thanks for all the input both on- and off- the list. We shall definitely look into these suggestions further and report again here in due course. Kind regards Sam On Tue, 9 Oct 2018 at 19:12, Sam Tang wrote: > Dear all > > Hello. We recently shot a crystal (a protein w

Re: [ccp4bb] Weird diffraction pattern

2018-10-09 Thread Sam Tang
...@diamond.ac.uk < colin.n...@diamond.ac.uk> wrote: > Sam > > Would this unit cell index some of the spots? > > a = 7.00 ± 0.04 A, b = 9.96 ± 0.05 A, c = 6.29 ± 0.04 A. > > Colin > > > > *From:* CCP4 bulletin board *On Behalf Of *Sam > Tang >

Re: [ccp4bb] Electrostatic Potential: Poisson-Boltzmann

2017-12-02 Thread Sam Tang
To add to the discussion, could I raise a relevant question about generating ESP (Apologies to Jiri if this distracts too much from your initial thread). In our structure in hand, the density for two conformations of the side chain are clearly seen and they could be modeled. This brings a bit of

[ccp4bb] Different loop conformations

2017-05-16 Thread Sam Tang
Dear all Sorry for the slightly off-topic thread. We are lucky enough to have recently solved a protein-ligand structure in P1 space to 2.4 A by molecular replacement using the apo-protein as model. The protein is known to have a flexible loop region of about 20 amino acid long. In the

Re: [ccp4bb] Modelling of ligand and Refmac5

2017-01-24 Thread Sam Tang
, Paul Emsley <pems...@mrc-lmb.cam.ac.uk> wrote: > On 24/01/2017 08:04, Sam Tang wrote: > >> >> I am trying to fit a small molecule ligand into a protein complex using >> Coot. The data was >> processed to P212121, at 2.6 A. What I did was to input a SMILES

[ccp4bb] Modelling of ligand and Refmac5

2017-01-24 Thread Sam Tang
(Also, the chain ID O was identified as OO?) In a test run I carried out rigid body refinement and the programme finished without issues. Is there a way I could rectify the above problem? Thanks in advance for your attention and input. Kind regards Sam Tang Biochemistry Programme, School of Life Sciences, CUHK

Re: [ccp4bb] Two SGs in one droplet?

2016-10-31 Thread Sam Tang
at the other. In the P6 case, the RNA ligand (in the > center of a hexameric protein) was rotationally averaged, but in the P1 > case it could be resolved. > > Best wishes > Kevin > > On Fri, Oct 28, 2016 at 6:13 AM, Sam Tang <samtys0...@gmail.com> wrote: > >>

[ccp4bb] Two SGs in one droplet?

2016-10-28 Thread Sam Tang
that there is no twinning), ~2.5 Angstrom Xtal2: P1 (53 60 79 106 105 98), ~3 Angstorm Would it be possible that the ligand changes the SG of the crystal so that only one of the forms contains the ligand? Any advice is appreciated and thanks a lot in advance for your input. Regards Sam Tang